• 산업공학
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• 제17권spc호
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• pp.97-102
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• 2004

AGV flowpath layout design is one of the most important steps for efficient AGV systems design. Since it was formulated by Gaskins & Tanchoco (1987), a unidirectional AGV flowpath layout design problem has been tackled by many researchers. However, the solution methods were traded off between the solution quality and the computational time. In this paper, a tabu search technique is applied to obtain a good solution for a relatively large problem in reasonable computational time. Specifically, fast construction algorithm for feasible initial solutions, long-term memory structure and neighbor solutions generation are adapted to the problem characteristics and embedded in the tabu search algorithm. Also, sets of computational experiments show that the proposed tabu search algorithm outperforms to the Ko and Egbelu's algorithm (2003).

• 산업공학
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• 제17권4호
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• pp.440-449
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• 2004

The OERA(Offensive Earned-Run Average) is a methodology for the performance evaluation of baseball players, which is based on a well- known Markov chain model. The DEA(Data Envelopment Analysis) is an LP-based evaluation technique for performance analysis of DMUs (Decision Making Units), whose production activities are characterized by multiple inputs and outputs. In this paper, the performances of Korean professional baseball players are analytically evaluated using both OERA and DEA methods. We discuss methodological strengths and drawbacks of two kinds of baseball evaluation techniques, by comparing both results. Finally to overcome the shortcomings of both methods, we develop a new analytical approach for baseball evaluation by combining OERA with DEA.

• 산업공학
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• 제10권2호
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• pp.69-77
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• 1997

Material handling equipment such as container cranes and transtainer cranes have made larger and faster to improve the efficiency of container handling. As conditions of use in container terminal have become severe, and also the automation level required has become higher. For the high level automation for transtainer crane, the following characteristics have to be developed 1) Container Terminal Operation & Planning System with high efficiency. 2)Autosteering System of transtainer crane with precise position sensing system using image processing and feedback control system. 3)Automatic Position Identification System with transponder. We have developed an AGSS(Automatic Gantry Steering System) of transtainer crane with image processing technology preferentially. In this paper, the system will be introduced.

• 산업공학
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• 제15권1호
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• pp.64-72
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• 2002

Broaching machine is widely used for machining inner shaped slots in the work-pieces, and provides vertical motion (usually hydraulically powered) between tool and work-piece. In this study, we modelled the tool life process and investigated economic tool life of broaching machine. Tool life process is divided into wear-process and succeeding failure process. Wear process is defined as machining wear and failure process as 'chipping' occurred by random shock. We modelled wear process as linear regression function for products amounts and assumed failure process as Poisson process. Economic tool life is defined as the number of lots which minimizes average tool related cost per lot and analyzed by using age replacement policy technique. As tool-related cost factors, we consider tool replacement cost, tool maintenance cost and quality costs of products. The results of this study can be applied to analyze life process of general machining tools.

• 산업공학
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• 제15권1호
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• pp.55-63
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• 2002

This paper utilizes the FIDO methodology (Function, Information, Dynamic, Organization modeling) which is an enterprise modeling tool that can describe inter-organizational interaction (specifically between prime and sub contractors in this experiment). FIDO follows the standard IDEFO rules in order to demonstrate how a cascading information flow can evolve from a customer to a prime to a subcontractor in a concurrent manner, in a supply chain environment. Background on these processes is presented, followed with the newly derived process and methodology. This is presented in a supply chain management context, and results from an actual experiment at Motorola utilizing subcontractors that supply custom machine parts is presented and reviewed.

• 산업공학
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• 제11권3호
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• pp.55-63
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• 1998

In this study we consider a CONWIP system in which the processing times at each station follow an exponential distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied instantaneously are assumed to be lost. We assume that the lot size at each station is greater than one. For this system we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of parts at each station, average number of parts at each station and the proportion of lost demands. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. A recursive technique is used to solve the subnetwork in the application of the product-form approximation method. To test the accuracy of the approximation method, the results obtained from the approximation method were compared with those obtained by simulation. Comparisons with simulation have shown that the accuracy of the approximate method is acceptable.

• 산업공학
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• 제5권2호
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• pp.19-27
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• 1992

The ABC analysis is a widely used inventory control technique which consists of classifying inventory items into three categories according to annual dollar usage and concentrating managerial efforts on the high value items. But its major weakness is that the classification is somewhat arbitrary and is made in the light of single criterion, the annual usage. In this paper, a modified approach using TOPSIS is proposed where 1) the inventory items are ranked, rather than classified into three categories, in the order of relative importance and 2) the latter is determined by considering the multiple criteria such as annual usage, difficulty of procurement, lead time and shelf life. A case study was performed with the field data from a company producing electronical parts. The rank order produced by TOPSIS was judged quite reasonable by the company inventory control manager.

• 산업공학
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• 제5권2호
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• pp.29-37
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• 1992

An approach to Just-In-Time for small job-shop-type manufacturers is presented. This is aimed at those who understand the pull production system, however, cannot afford either swift changeover in workcenters or frequent delivery to customers. First, as a production planning technique, a lot-sizing model entitled Multilevel Least Total Cost Model(MLTCM) is developed; The production order quantities of each components be those requiremensts of the end item production lot. The contribution of MLTCM is shown via simulation. Then, a framework of the Kanban operations is designed; A Production Control Kanban is introduced as a communication tool with Production Kanban in a job-shop.

• 산업공학
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• 제24권3호
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• pp.173-186
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• 2011

In this paper, we evaluate life annuity plans for Korean pre-retired single and married couple participating Korea National Pension (KNP) and find optimal life annuity strategy by using utility-based measurements called AEW (Annuity Equivalent Wealth). Specifically, we extend a previous study to obtain a detailed optimal combination of annuitizing age and wealth in terms of percentage of net wealth at the time of retirement. A nonlinear optimization model is formulated with the objective of maximizing utility on consumption and bequest, and the dynamic programming (DP) technique is used to solve this problem. We find that there exist consistent patterns in optimal combinations of annuitizing age and wealth. Also, for all cases the optimal combination is significantly better than several other combinations. The results indicate that using the optimal approach can be beneficial to practitioners in insurance industry and prospective purchasers of life annuity. We conclude the paper with some discussions and suggestions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2702-2704
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• 2005

This paper proposes the genetic algorithm (GA)-based fuzzy modeling method for intelligent tracking of a maneuvering target. When the maneuvering to turn or taking evasive action, the performance of the standard Kalman filter has been degraded because residual between the modeled target dynamics and the actual target dynamics. To solve this problem, the state prediction error is minimized by the intelligent estimation method. Then, this filter is corrected by measurement corrections which is the fuzzy system. The performance of the proposed method is compared with those of the input estimation(IE) technique through computer simulation.